Portable terminal equipped with a recording medium

ABSTRACT

The invention relates to power saving in portable terminals ( 100 ) with recording media ( 200 ). Conventionally, there is the problem that a battery ( 104 ) in the portable terminal ( 100 ) may become exhausted and as a result the original function of the terminal cannot be performed. To solve this problem, when the remaining battery capacity is low, the invention controls power supply ( 108 ) to the recording media ( 200 ) and clock supply ( 110 ) to a CPU ( 202 ) in the recording media ( 200 ) so as to reduce power supplied to the recording media ( 200 )

TECHNICAL FIELD

[0001] The present invention relates to power saving techniques forportable terminals equipped with recording media.

BACKGROUND ART

[0002] With recent improvements in semiconductor technology, recordingmedia such as SD memory cards have shrunk in size and grown in capacity.As a result, recording media are increasingly equipped in portableterminals such as mobile phones and PDAs and put to use. In other words,portable terminals that are equipped with recording media which storecontent such as image and music data, and that realize an additionalfunction of content reproduction as well as their original function ofcommunication and the like, are becoming widely available.

[0003] To execute such an additional function in a portable terminalequipped with a recording medium, the recording medium needs to beoperated. This requires a large amount of power to be supplied from abattery in the portable terminal to the recording medium.

[0004] However, when the remaining capacity of the battery is low, ifthe execution of the additional function is continued, the battery inthe portable terminal may become exhausted. When this happens, theportable terminal cannot perform its original function.

DISCLOSURE OF INVENTION

[0005] The present invention was conceived in view of the problem withthe background art, and has an object of providing a portable terminalthat can prevent its original function as a portable terminal frombecoming unable to be performed as a result of performing an additionalfunction associated with an operation of a recording medium, when aremaining battery capacity is low.

[0006] The stated object can be achieved by a portable terminalincluding a battery for supplying power to parts of the portableterminal and to a recording medium equipped in the portable terminal,the portable terminal including: a remaining battery capacity monitoringunit operable to monitor a remaining capacity of the battery; and apower controlling unit operable to exercise control so that the powersupplied to the recording medium is reduced, when the remaining capacityis below a predetermined level.

[0007] With this construction, if the remaining battery capacity isbelow the predetermined level, the amount of power consumed by therecording medium is reduced. Accordingly, in a portable terminal thatperforms only its original function when a recording medium is notequipped but that can also perform an additional function when therecording medium is equipped and operated, it is possible to prevent theportable terminal from becoming unable to perform its original functionas a result of continuously performing the additional function, when aremaining battery capacity is low.

[0008] Here, the control exercised by the power controlling unit may beto stop the power supply to the recording medium when the remainingcapacity is below the predetermined level.

[0009] With this construction, if the remaining battery capacity isbelow the predetermined level, the power supply to the recording mediumis cut off. This disables the execution of the additional function, andallows the portable terminal to perform only its original function.

[0010] Here, the recording medium may include a CPU, wherein the controlexercised by the power controlling unit is to stop a supply of a clockto the CPU in the recording medium when the remaining capacity is belowthe predetermined level.

[0011] With this construction, if the remaining battery capacity isbelow the predetermined level, the CPU in the recording medium does notoperate. This reduces the power consumption associated with theexecution of the additional function, and allows the portable terminalto perform its original function with priority.

[0012] Here, the recording medium may include a CPU, wherein the controlexercised by the power controlling unit is to decrease a frequency of aclock supplied to the CPU in the recording medium when the remainingcapacity is below the predetermined level.

[0013] With this construction, if the remaining battery capacity isbelow the predetermined level, the clock frequency for the CPU in therecording medium is decreased. This reduces the power consumptionassociated with the execution of the additional function, and allows theportable terminal to perform its original function with a higherpriority while also performing the additional function.

[0014] Here, the portable terminal may further include a setting unitoperable to set the predetermined level in accordance with a useroperation, and hold the predetermined level.

[0015] With this construction, each individual user can set theremaining battery threshold level for reducing the power supplied to therecording medium. This enables control that depends on what relativeimportance each individual user attaches to the original function andthe additional function.

[0016] Here, the recording medium may include a CPU, wherein the controlexercised by the power controlling unit is to (a) stop the power supplyto the recording medium, when the remaining capacity is not less than afirst level but below a second level, (b) stop a supply of a clock tothe CPU in the recording medium, when the remaining capacity is not lessthan the second level but below a third level, and (c) decrease afrequency of the clock supplied to the CPU in the recording medium, whenthe remaining capacity is not less than the third level but below afourth level.

[0017] With this construction, control can be exercised so as togradually reduce the power consumption of the recording medium inaccordance with the remaining battery capacity.

[0018] The stated object can also be achieved by a portable terminalthat has a communication function and a content reproduction function,and includes a battery for supplying power to parts of the portableterminal and to a recording medium which stores content and is equippedin the portable terminal, the portable terminal including: a remainingbattery capacity monitoring unit operable to monitor a remainingcapacity of the battery; and a power controlling unit operable toexercise control so that the power supplied to the recording medium isreduced, when the remaining capacity is below a predetermined level.

[0019] With this construction, if the remaining battery capacity isbelow the predetermined level in the portable terminal whose originalfunction is the communication function, the power consumption of therecording medium is reduced. This prevents the portable terminal frombecoming unable to perform the communication function as a result ofcontinuously performing the content reproduction function.

BRIEF DESCRIPTION OF DRAWINGS

[0020]FIG. 1 shows a construction of a portable terminal according to anembodiment of the invention, and a construction of a recording mediumconnected to the portable terminal.

[0021]FIG. 2 shows a detailed construction of a content reproductionfunction unit shown in FIG. 1.

[0022]FIG. 3 shows the relation between remaining battery capacity andpower control.

[0023]FIG. 4 is a flowchart showing a power saving control operation ofthe portable terminal.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] The following describes an embodiment of the present invention byreferring to the drawings.

[0025] (Construction of a Portable Terminal)

[0026]FIG. 1 shows a construction of a mobile phone to which theembodiment of the invention relates, and a construction of a recordingmedium that is connected to the mobile phone. A mobile phone 100 has anoriginal function as a telephone, and an additional function ofreproducing content recorded on a recording medium 200. The mobile phone100 includes a communication function unit 101, a call function unit102, a content reproduction function unit 103, a battery 104, aremaining battery capacity monitoring unit 105, a power saving unit 106,a power supply controlling unit 107, a power supplying unit 108, a clockcontrolling unit 109, a clock generating unit 110, and an I/F unit 111.

[0027] The communication function unit 101 performs signal processing,modulation/demodulation, and the like, for transmitting and receivingvoice.

[0028] The call function unit 102 inputs/outputs the voice, and is madeup of a microphone and a speaker.

[0029] The communication function unit 101 and the call function unit102 realize the original function as a mobile phone.

[0030] The content reproduction function unit 103 realizes theadditional function of the mobile phone 100, and performs reproductionof content recorded on the recording medium 200 and necessary processesfor the reproduction. FIG. 2 shows a detailed construction of thecontent reproduction function unit 103. The details of the contentreproduction function unit 103 are explained below, with reference tothe drawing.

[0031] An authenticating unit 400 performs authentication with a CPU 202in the recording medium 200. If the authentication is successful, theCPU 202 permits the mobile phone 100 to access a secure data area 206 ina flash memory 205. A medium key & ID acquiring unit 402 reads a mediaID and medium key information from the secure data area 206. A contentkey decryption key generating unit 401 generates a content keydecryption key from the read media ID and medium key information. Acontent key acquiring unit 404 reads a content key from the secure dataarea 206. A content key decrypting unit 403 decrypts the read contentkey using the generated content key decryption key. A content acquiringunit 406 reads content from a data area 207 in the flash memory 205. Acontent decrypting unit 405 decrypts the read content using thedecrypted content key. A content reproducing unit 407 reproduces thedecrypted content.

[0032] The battery 104 holds power for operating the mobile phone 100and the recording medium 200.

[0033] The remaining battery capacity monitoring unit 105 measures avoltage of the battery 104 at predetermined time intervals, to monitorthe remaining capacity of the battery 104.

[0034] The power saving unit 106 controls power consumption of therecording medium 200, by instructing the power supply controlling unit107 and the clock controlling unit 109 in accordance with the level ofthe remaining battery capacity.

[0035]FIG. 3 shows the relation between the remaining battery level andthe power control. As illustrated, when the remaining battery level is“4” (6 to 8 minutes when converted to time during which the mobile phone100 performs its original function only), the power supply is normal,and the clock frequency is normal. When the remaining battery level is“3” (4 to 6 minutes), the power supply is normal, and the clockfrequency is low. When the remaining battery level is “2” (2 to 4minutes), the power supply is normal, and the clock is stopped. When theremaining battery level is “1” (less than 2 minutes), both the powersupply and the clock are stopped.

[0036] The power supplying unit 108 takes power from the battery 104,and supplies it to the mobile phone 100 and the recording medium 200.

[0037] The power supply controlling unit 107 controls the power supplyof the power supplying unit 108 to the recording medium 200, accordingto instructions from the power saving unit 106.

[0038] The clock generating unit 110 generates a clock and supplies itto the CPU 202 in the recording medium 200.

[0039] The clock controlling unit 109 controls the clock generation ofthe clock generating unit 110, according to instructions from the powersaving unit 106.

[0040] The I/F unit 111 exchanges data with the recording medium 200.

[0041] The recording medium 200 includes a power receiving unit 201, theCPU 202, an I/F unit 203, and the flash memory 205.

[0042] The power receiving unit 201 receives power and supplies it toeach construction element in the recording medium 200.

[0043] The CPU 202 performs authentication with the mobile phone 100,control of reading/writing data, and the like.

[0044] The I/F unit 203 exchanges data with the mobile phone 100.

[0045] The flash memory 205 has the secure data area 206 and the dataarea 207.

[0046] The secure data area 206 is an area which can be accessed by themobile phone 100 only when the authentication is successful. The securedata area 206 stores the media ID, the medium key information, and thecontent key.

[0047] The media ID is a number uniquely given to the recording medium200 for identifying the recording medium 200. The media ID is stored inthe recording medium 200 at the time of manufacturing.

[0048] The medium key information is used to generate the content keydecryption key, together with the media ID.

[0049] The content key is a key for decrypting the content, and isstored having been encrypted by a secret key cipher. To decrypt thecontent key, the content key decryption key is used.

[0050] The data area 207 is an area which can be accessed by the mobilephone 100 without performing the mutual authentication. The data area207 stores the content which has been encrypted by a secret key cipher.Here, the content is MP3 music data.

[0051] (Operation)

[0052] An operation of the mobile phone 100 is explained below.

[0053]FIG. 4 is a flowchart showing a power saving control operation ofthe mobile phone 100.

[0054] The power saving control operation starts when the recordingmedium 200 is connected to the mobile phone 100.

[0055] First, the remaining battery capacity monitoring unit 105measures the remaining capacity of the battery 104 at predetermined timeintervals (S301 and S302).

[0056] The power saving unit 106 checks whether the level of theremaining battery capacity has changed (S303). If the remaining batterylevel has not changed, the operation returns to step S301. Otherwise,the operation proceeds to the next step.

[0057] When the remaining battery level is “4”, the power saving unit106 instructs the power supply controlling unit 107 to control the powersupply of the power supplying unit 108 to the recording medium 200 to benormal. The power supply controlling unit 107 accordingly controls thepower supplying unit 108 to switch to the normal power supply, if thepower supply of the power supplying unit 108 is not normal (S304 andS305).

[0058] Also, the power saving unit 106 instructs the clock controllingunit 109 to control the clock frequency of the clock generating unit 110to be normal. The clock controlling unit 109 accordingly controls theclock generating unit 110 to switch to the normal clock frequency, ifthe clock frequency of the clock generating unit 110 is not normal(S306).

[0059] When the remaining battery level is “3”, the power saving unit106 instructs the power supply controlling unit 107 to control the powersupply of the power supplying unit 108 to be normal. The power supplycontrolling unit 107 accordingly controls the power supplying unit 108to switch to the normal power supply, if the power supply of the powersupplying unit 108 is not normal (S307 and S308).

[0060] Also, the power saving unit 106 instructs the clock controllingunit 109 to control the clock frequency of the clock generating unit 110to be low. The clock controlling unit 109 accordingly controls the clockgenerating unit 110 to switch to the low clock frequency, if the clockfrequency of the clock generating unit 110 is not low (S309).

[0061] When the remaining battery level is “2”, the power saving unit106 instructs the power supply controlling unit 107 to control the powersupply of the power supplying unit 108 to be normal. The power supplycontrolling unit 107 accordingly controls the power supplying unit 108to switch to the normal power supply, if the power supply of the powersupplying unit 108 is not normal (S310 and S311).

[0062] Also, the power saving unit 106 instructs the clock controllingunit 109 to stop the clock generation of the clock generating unit 110.The clock controlling unit 109 accordingly controls the clock generatingunit 110 to stop the clock generation, if the clock generation of theclock generating unit 110 is not stopped (S312).

[0063] When the remaining battery level is “1”, the power saving unit106 instructs the power supply controlling unit 107 to stop the powersupply of the power supplying unit 108. The power supply controllingunit 107 accordingly controls the power supplying unit 108 to stop thepower supply, if the power supply of the power supplying unit 108 is notstopped (S313 and S314).

[0064] Also, the power saving unit 106 instructs the clock controllingunit 109 to stop the clock generation of the clock generating unit 110.The clock controlling unit 109 accordingly controls the clock generatingunit 110 to stop the clock generation, if the clock generation of theclock generating unit 110 is not stopped (S315).

[0065] If the recording medium 200 is removed from the mobile phone 100,the power saving control operation ends. Otherwise, the operationreturns to step S301 to repeat the power saving control (S316).

[0066] (Conclusion)

[0067] As described above, the mobile phone according to the aboveembodiment reduces the power supplied to the recording medium when theremaining battery capacity is low, with is being possible to prevent theoriginal function of the mobile phone from becoming unable to beperformed.

[0068] (Modifications)

[0069] (1) Regarding the Recording Medium

[0070] The recording medium of the above embodiment may be a memory cardsuch as a compact flash card, a smart card, a memory stick, a multimediacard, or an SD memory card.

[0071] Also, the recording medium may be a card that does not include aCPU, with the portable terminal controlling only the power supply to therecording medium.

[0072] (2) Regarding the Content

[0073] The above embodiment describes the case where the content is MP3electronic music data, but the invention is not limited to such. Forexample, the content may be electronic music data of AAC (Advanced AudioCoding), LPCM (Linear Pulse Code Modulation), or similar. Also, thecontent may be video data of JPEG (Joint Photographic Expert Group),MPEG 1/2/4, or the like. Further, the content may be electronic textdata of HTML (Hyper Text Markup Language) or the like, or an applicationsuch as a game.

[0074] (3) Regarding the Portable Terminal

[0075] The above embodiment takes a mobile phone as an example portableterminal, though this is not a limit for the invention, which may beapplied to any portable-type terminal, such as a PDA, a hand-held PC, ora notebook-sized PC, that supplies power to itself and to a recordingmedium equipped therein using a battery.

[0076] (4) Regarding the Notification in the Power Saving Procedure

[0077] Though the user is not notified of the power saving result in theabove embodiment, a message like the one indicating that the contentcannot be reproduced because of a low remaining battery capacity may bedisplayed.

[0078] (5) Regarding the Setting of the Remaining Battery Levels

[0079] The above embodiment describes the case where the remainingbattery levels for switching to the power saving control arepredetermined, but such levels may be set by the user.

[0080] (6) Regarding the Authentication

[0081] The above embodiment describes the case where the CPU 202 in therecording medium 200 performs the authentication with the authenticatingunit 400 in the mobile phone 100, but the invention should not belimited to such. For instance, a special chip for authentication may beequipped in the recording medium so as to perform the authentication.

INDUSTRIAL APPLICABILITY

[0082] The portable terminal of the present invention can be used as amobile phone that has a function of reproducing content recorded on arecording medium.

1. A portable terminal including a battery for supplying power to partsof the portable terminal and to a recording medium equipped in theportable terminal, comprising: a remaining battery capacity monitoringunit operable to monitor a remaining capacity of the battery; and apower controlling unit operable to exercise control so that the powersupplied to the recording medium is reduced, when the remaining capacityis below a predetermined level.
 2. The portable terminal of claim 1,wherein the control exercised by the power controlling unit is to stopthe power supply to the recording medium when the remaining capacity isbelow the predetermined level.
 3. The portable terminal of claim 1,wherein the recording medium includes a CPU, and the control exercisedby the power controlling unit is to stop a supply of a clock to the CPUin the recording medium when the remaining capacity is below thepredetermined level.
 4. The portable terminal of claim 1, wherein therecording medium includes a CPU, and the control exercised by the powercontrolling unit is to decrease a frequency of a clock supplied to theCPU in the recording medium when the remaining capacity is below thepredetermined level.
 5. The portable terminal of claim 1, furthercomprising a setting unit operable to set the predetermined level inaccordance with a user operation, and hold the predetermined level. 6.The portable terminal of claim 1, wherein the recording medium includesa CPU, and the control exercised by the power controlling unit is to (a)stop the power supply to the recording medium, when the remainingcapacity is not less than a first level but below a second level, (b)stop a supply of a clock to the CPU in the recording medium, when theremaining capacity is not less than the second level but below a thirdlevel, and (c) decrease a frequency of the clock supplied to the CPU inthe recording medium, when the remaining capacity is not less than thethird level but below a fourth level.
 7. A portable terminal that has acommunication function and a content reproduction function, and includesa battery for supplying power to parts of the portable terminal and to arecording medium which stores content and is equipped in the portableterminal, comprising: a remaining battery capacity monitoring unitoperable to monitor a remaining capacity of the battery; and a powercontrolling unit operable to exercise control so that the power suppliedto the recording medium is reduced, when the remaining capacity is belowa predetermined level.
 8. A power control method for use in a portableterminal that includes a battery for supplying power to parts of theportable terminal and to a recording medium equipped in the portableterminal, comprising: a remaining battery capacity monitoring step formonitoring a remaining capacity of the battery; and a power controllingstep for exercising control so that the power supplied to the recordingmedium is reduced, when the remaining capacity is below a predeterminedlevel.
 9. A computer-readable storage medium storing a program forexecuting a power control operation on a computer which includes abattery for supplying power to parts of the computer and to a recordingmedium equipped in the computer, the program comprising: a remainingbattery capacity monitoring step for monitoring a remaining capacity ofthe battery; and a power controlling step for exercising control so thatthe power supplied to the recording medium is reduced, when theremaining capacity is below a predetermined level.
 10. A program forexecuting a power control operation on a computer which includes abattery for supplying power to parts of the computer and to a recordingmedium equipped in the computer, comprising: a remaining batterycapacity monitoring step for monitoring a remaining capacity of thebattery; and a power controlling step for exercising control so that thepower supplied to the recording medium is reduced, when the remainingcapacity is below a predetermined level.